Pneumatically expansible mandrel

ABSTRACT

A pneumatically expansible mandrel is formed in an extruded aluminum body section that is mounted on and surrounds an extruded tubular steel core section. Multifaceted outer and inner mating surfaces on the two sections ensure proper torque transmission. The overall unit has strength comparable to a solid steel construction but at lower cost and without appreciably greater weight than a solid aluminum construction.

United States Patent Inventor Michael M. Young 510 Tea Rose Lane, Cherry Hill, NJ. 08034 Appl. No. 365,003

Filed Oct. 9, 1969 Patented July 13, 1971 PNEUMATICALLY EXPANSIBLE MANDREL 8 Claims, 3 Drawing Figs.

int. Cl B65h 75/24 Field of Search 242/72,

[56] References Cited UNITED STATES PATENTS 2,621,867 12/1952 Grettve 242/72 B 3,032,288 5/1962 Tidland 242/72 B 3,214,109 10/1965 Gadde et a1 242/72 B Primary Examiner-George F. Mautz Assistant Examiner-Gregory A. Walters AttorneyMorton C. Jacobs ABSTRACT: A pneumatically expansible mandrel is formed in an extruded aluminum body section that is mounted on and surrounds an extruded tubular steel core section. Multifaceted outer and inner mating surfaces on the two sections ensure proper torque transmission. The overall unit has strength comparable to a solid steel construction but at lower cost and without appreciably greater weight than a solid aluminum construction.

PAIENTEU JUL 1 3 1971 INVENTOR. MICHAEL M. YOUNG Wjfl ATTORNEY.

This invention relates to an expansible mandrel or shaft, of

the type that is pneumatically operated and used for internally gripping rolls of paper and other webs during the winding, unwinding, slitting, coating, printing, sheeting or other processing of the web materials, be they wound in sleeves or sleeveless.

Expansible mandrels of this type are described, for example, in U.S. Pats. No. 3,223,341, issued Dec. 14, 1965; No. 3,214,109, issued Oct. 26, 1965; and No. 2,621,867, issued Dec. 16, 1952. Such mandrels have been fabricated from a solid core of aluminum which is extruded in a generally cylindrical shape with notches in the outer surface and spaced therearound, and extending lengthwise of the mandrel. The notches each contain a pneumatically inflatable tube and a rail. The rails move radially outward in an expanded position when the tubes are inflated, and the expanded rails engage internally of a sleeve to be driven. The notches at their outer edges have abutment ribs that overhang and engage ribs along the sides of the expanded rails to retain the latter in the notches.

Rolls of web material supported by such mandrels may weigh as much as 500 to 1,000 pounds and may require mandrels that are 3 feet or more in length. Such loads are excessive for the strength of the aluminum core which tends to bend under the loading. The replacement of the aluminum by a denser metal such as steel requires an expensive and slow milling of the notches.

SUMMARY OF THE INVENTION It is an object of this invention to provide a new and improved pneumatically expansible mandrel.

Another object is to provide such a new and improved mandrel that is light in weight and of superior strength.

Another object is to provide such a new and improved mandrel that can be fabricated of extruded materials.

Another object is to provide such a new and improved mandrel that is capable of exerting maximum torque between the expanding rails and the bearing or driving surface of the mandrel.

Another object is to provide a new and improved mandrel having hardened bearing surfaces for longer useful life.

In accordance with one form of the invention, a pneumatically expansible mandrel is constructed with two sections of different metals. The central core of the mandrel is formed of extruded and rerolled steel tubing having a multifaceted outer surface. The outer body of the mandrel is extruded from aluminum with a hollow center and with notches in the outer surface. The hollow center of the aluminum body is multifaceted to mate with the steel core for maximum torque transmission between the core and body extrusions when one is mounted on the other. In one embodiment in which five notches for rails are formed in the aluminum body, the steel tubing is formed with five plane faces, and the hollow center of the aluminum body is similarly formed with each face generally parallel to the base of a notch. The radii of the inscribed and circumscribed circles of the pentagon-shaped hollow center of the body are made as large as possible to obtain greatest strength characteristics in the core extrusion. In this fashion, the overall metal structure has strength comparable to that of solid steel but at substantially lower manufacturing cost, and its weight is about the same as that ofsolid aluminum.

BRIEF DESCRIPTION OF THE DRAWING The foregoing and other objects of this invention, the various features thereof, as well as the invention itself, may be more fully understood from the following description when read together with the accompanying drawing, in which:

FIG. 1 is an exploded perspective view of one form of an expansible mandrel embodying this invention;

FIG. 2 is an end view of the assembled mandrel of FIG. 1; and

FIG. 3 is a sectional view taken on the line 3-3 of FIG. 2.

In the drawing, corresponding parts are referenced throughout by similar numerals.

DESCRIPTION OF A PREFERRED EMBODIMENT surface of the core 14. The mandrel is formed by assembling,

the body section onto the core section in tight frictional relation; thismay be done with the sections immersed in a suitable lubricating bath and by forcing the core into the body section.

The body section 12 is also extruded in-any desired length, and notches 16 extending the full length of the body are also formed with the extrusion. Various numbers of notches-may be provided depending on the particular application and specifications; each notch carries an expansible. gripping rail 18 which is moved outwardly by a pneumatically inflatable tube 20 (a suitable construction of which is knownin the art and described in U.S. Pat. No. 3,223,341). The rails-18 each have laterally extending ribs 22 that abut inwardly extending ribs 24 at the outer face of the notch, whereby the expanded rails are retained in gripping position under the actuation of the inflated tube 20.

A steel plug 26, suitable retained in the core section 14, has a central air passage 28 that opens at the inner endonto a plurality of radial passages 30, each of which extends through the core and body sections into one of the notches and leads to a nipple inlet to the inflatable tube in the associated notch 16. The outer end of passage 28 is closed bya suitable pneumatic valve 32, which is recessed in a protected position within the tubular core 14. In operation, air under pressure may be applied via the valve 32, passage 28, passages 30 to the inflatable tubes 20 in the notches 16 to expand the rails to their gripping position. The other end of the core 14 may also receive a plug 34 to close off that end of the steel tube and to provide a suitable means for mounting the unit on a lathe for machining operations.

The steel core 14 is formed in lengths somewhat longer than the body 12, whereby a bearing surface 36, 38 may be provided by means of the steel tube projecting beyond the body at each end. The cylindrical bearing surfaces 36, 38 are fabricated by machining down the flat outer faces of the steel tube after the body 12 is assembled on the core 14.

The ends of the inflatable tube 20 are clamped in position by clamping elements 40 42, one at each end, and by threaded fasteners such as screws 44 that pass through holes 41 in the clamps 40 and 42, holes 43 in the ends of the tube 20, and holes 45 in rubber shields 46 that seat between the tube 20 and the clamps 40 and 42. In order to prevent air leaks between the mating flat surfaces 52 and 54 of body 12 and core 14, respectively, a blind insert 48 is used for threaded engagement with each screw 44. The blind inserts 48 are closed at their bottom ends and externally threaded, and their outer threaded surfaces are covered with a sealing compound and screwed into a hole tapped through the floor of the notch 16 into both the body 12 and core 14. The sealing compound prevents air leaks, and the internal threads of inserts 48 are designed to engage the threads of screws 44. Air leaks that might occur at the mating-flat surfaces 52 and 54 of body 12 and core 14 along radial passages 30 are prevented by inserting an airtight sleeve 50 in each passage 30 or by lining the passages 30 with sealing compound.

The aluminum extrusion for the body section 12 has a pentagon-shaped hollow center, for the illustrated embodiment.

Each flat surface 52 of the body section 12 is designed to be generally parallel to the floor of an associated notch 16. The latter are uniformly spaced around the periphery of the body section 12, and accordingly the surfaces 52 form a regular pentagon in cross section. The outer flat surfaces 54 of the core section 14 are similar to the surfaces 52, to provide the proper mating thereof when the core 14 is inserted in the body 12. The perpendicular distance (radius of the inscribed circle) from the center of the body section 12 to the surface 52 is designed to be as large as possible, as is the distance from the center of the body section 12 to the vertices ofthe pentagon (radius of the circumscribed circle). Thereby the greatest strength characteristics are obtained for the core section 14.

The mating surfaces 52 and 54 transmit the torques between the core 14 and body 12, with one being the driving element and the other the driven, in ordinary usage. For maximum capability of torque transmission between the core and the body, as many surfaces 52 as possible should be provided, consistent with the other design requirements. Thus, in the case of a mandrel with five notches 16, a pentagon core section for the mating surfaces 52 and 54 ensures optimum torque capability, together with optimum radii lengths where the pentagon sides are formed generally parallel to the floor of the notches 16. In a similar fashion, for other designs of mandrels with different numbers of notches, the cross section of the hollow center of the body section is preferably formed to have the same number of sides as the notches. Thereby, the flat surfaces can extend to intersect between adjacent notches 16 to provide an optimum length of the circumscribed-circle radius and consequently an optimum strength characteristic in the core section 14.

The flat torque-transmitting surfaces 52 and 54 are readily extruded in various desired lengths for the body section 12 and core section 14. After the core is inserted in the body, the portions that project beyond the body are readily turned down to provide the cylindrical bearing surfaces 36 and 38. Since these surfaces are formed on the steel extrusion, they provide excellent and long-wearing bearings.

The mandrel provided by this invention incorporates generally all of the advantages of the all-aluminum construction, with the strength and other advantages of an all-steel construction. The body section 12 is extruded in a fashion similar to the all-aluminum construction so that the detailed geometry of the notches 16 may be formed by the extrusion in the same way as in the all-aluminum construction. These notches receive the various elements (the tube 20, washers 46, and the tube clamps 40) in the same fashion, whereby the expanded gripping elements 18 may slide radially outwardly and back within the notches. The torque-transmission characteristic is comparable to that of an all-aluminum mandrel. The overall weight of the assembled mandrel of this invention is about that of an all-aluminum mandrel; the weight of the tubing for the steel core 14 is about the same as that of the comparable solid aluminum. However, the strength of the mandrel of this invention is largely that of the steel tubing of the core section 14, which is substantially that of an all-steel construction. In addition, hardened bearing surfaces 36 and 38 are provided, corresponding to those which would be available with an all-steel construction.

Accordingly, a new and improved pneumatically expansible mandrel is provided which can be made principally of extruded materials so that its cost of manufacture is relatively low, notwithstanding that the overall strength of the unit is comparable to that of a solid steel construction. A preferred form of the invention has been described above and illustrated in the drawing; various modifications thereof will be apparent to those skilled in the art. For example, the mandrel may be provided with various numbers of gripping rails 18 spaced around the periphery thereof, and the cross-sectional shape of the mating flat surfaces in the body and core sections would be formed to correspond in number. Though this is a preferred construction of the invention, the mandrel may also be constructed with the number of such flat mating surfaces different from the number of gripping rails. Other modifications of this invention will be apparent from the foregoing description, which is presented as illustrative of the invention What I claim is:

1. In a pneumatically expansible mandrel having an elongated body, a notch in the outer surface of said body, and expanding gripping means movably mounted in said notch including pneumatic means for actuating said gripping means;

an improved body construction comprising:

an extruded aluminum body section; and an extruded steel tubular core section;

said sections having mating planar faces internally of the body section and externally of the core section for transmission of torques therebetween.

2. A pneumatically expansible mandrel as set forth in claim 1 wherein the body section has a generally cylindrical outer surface, a plurality of notches are formed in'said outer body surface and spaced therearound, and a separate one of said gripping means in each of said notches;

said body and core sections each having a plurality of planar faces corresponding to the number ofsaid notches.

3. A pneumatically expansible mandrel as set forth in claim 2 wherein said planar faces are each formed adjacent to one of said notches.

4. A pneumatically expansible mandrel as set forth in claim 3 wherein adjacent ones of said planar faces intersect between adjacent ones of said notches.

5. A pneumatically expansible mandrel as set forth in claim 2 wherein a plug is secured internally of said tubular core section, a pneumatic passage extends axially through said plug, a valve in one end of said axial passage and a plurality of radial passages extend from the other end of said axial passage through said core and body sections to said pneumatic means.

6. A pneumatically expansible mandrel as set forth in claim 5 wherein said radial passages each include a lining extending therealong and across the mating surfaces of said body and core sections.

7. A pneumatically expansible mandrel as set forth in claim 1 wherein said steel core section is longer than and projects from opposite ends of said body section; and the projecting parts of said core section are formed in circular bearing surfaces.

8. A pneumatically expansible mandrel as set forth in claim 1 wherein a plug is secured internally of said tubular core section, and a pneumatic passage is provided therein for communication with said pneumatic means in said notch. 

1. In a pneumatically expansible mandrel having an elongated body, a notch in the outer surface of said body, and expanding gripping means movably mounted in said notch including pneumatic means for actuating said gripping means; an improved body construction comprising: an extruded aluminum body section; and an extruded steel tubular core section; said sections having mating planar faces internally of the body section and externally of the core section for transmission of torques therebetween.
 2. A pneumatically expansible mandrel as set forth in claim 1 wherein the body section has a generally cylindrical outer surface, a plurality of notches are formed in said outer body surface and spaced therearound, and a separate one of said gripping means in each of said notches; said body and core sections each having a plurality of planar faces corresponding to the number of said notches.
 3. A pneumatically expansible mandrel as set forth in claim 2 wherein said planar faces are each formed adjacent to one of said notches.
 4. A pneumatically expansible mandrel as set forth in claim 3 wherein adjacent ones of said planar faces intersect between adjacent ones of said notches.
 5. A pneumatically expansible mandrel as set forth in claim 2 wherein a plug is secured internally of said tubular core section, a pneumatic passage extends axially through said plug, a valve in one end of said axial passage and a plurality of radial passages extend from the other end of said axial passage through said core and body sections to said pneumatic means.
 6. A pneumatically expansible mandrel as set forth in claim 5 wherein said radial passages each include a lining extending therealong and across the mating surfaces of said body and core sections.
 7. A pneumatically expansible mandrel as set forth in claim 1 wherein said steel core section is longer than and projects from opposite ends of said body section; and the projecting parts of said core section are formed in circular bearing surfaces.
 8. A pneumatically expansible mandrel as set forth in claim 1 wherein a plug is secured internally of said tubular core section, and a pneumatic passage is provided therein for communication with said pneumatic means in said notch. 